A novel radiological classification for displaced os coccyx: the Benditz-König classification

Area of Science:

• Orthopedics
• Radiology
• Pain Management

Background:

• Coccygodynia (tailbone pain) presents a treatment challenge with a lack of clear surgical selection criteria.
• Developing a standardized radiological classification is crucial for improving surgical decision-making in coccygodynia cases.

Purpose of the Study:

• To establish a novel radiological classification system for coccygodynia.
• To correlate radiological findings with patient treatment outcomes.

Main Methods:

• Retrospective analysis of standing and sitting X-rays from 138 coccygodynia patients (2018-2020).
• Measurement of sacro-coccygeal angle (SCA), intra-coccygeal angle (ICA), and difference in intervertebral disc height (∆IDH).
• Classification of coccyges into four subtypes based on displacement and alignment.

Main Results:

• Four subtypes of displaced coccyges were identified: Type I (non-segmented, anterior pivot), Type II (multisegmented, anterior pivot), Type III (posterior pivot), and Type IV (anterior-posterior dissociation).
• Specific angular and disc height changes (SCA, ICA, ∆IDH) were associated with each subtype.
• 49 out of 138 patients underwent coccygectomy, with subtypes III and IV being more indicative of surgical intervention.

Conclusions:

• The proposed radiological classification aids in surgical decision-making for displaced coccyges.
• Standing and sitting X-rays offer a cost-effective and low-radiation alternative to CT and MRI for evaluating coccygodynia.
• Subtypes III and IV of the classification are strongly associated with the need for surgical treatment.